Metal Gear Solid, the first one. Before they started getting too ridiculous. Snake Eater comes a close second though.
I don't know I wasn't a fan of snake eater loved the 1st MGS tho. The 2nd MGS I prefered to snake eater mainly because it hadn't reached the level of stupid that were accustomed to now when someone says METAL GEAR SOLID.
It's a tie between the first Metal Gear and Silent Hill 2, for me.
Don't talk to me about the PS3 port, though. I'm not touching that thing with a ten-foot pole.
Best Konami game?
Hands down, Suikoden II.
I'm a huge Castlevania freak, so I'd go with the entire series...minus the N64 games and Curse of Darkness.
If I had to narrow, I'd go with Dawn of Sorrow. Took the awesome Symphony formula and just expanded it for me.